The invention relates to a control system of a seafood constant temperature machine. The control system comprises an outdoor draught fan, a compressor, a reversing valve, a control main board, a water temperature sensor, a defrosting sensor, a display operation panel, a transformer and a variable frequency water pump, wherein the reversing valve controls a flow direction of a refrigerating agent, the water temperature sensor is used for collecting water temperature information, the defrosting sensor is used for collecting defrosting information of the outdoor draught fan, the display operation panel is used for displaying a working state of the constant temperature machine and is capable of carrying out control operation, the transformer is used for supplying stable working voltage to the control main board, and the variable frequency water pump is capable of realizing liquid transportation; the outdoor draught fan, the compressor, the water temperature sensor, the defrosting sensor, the transformer, the display operation panel and the variable frequency water pump are all connected with the control main board. According to the control system disclosed by the invention, the working state of the constant temperature machine can be displayed in real time, the operation is convenient and fast, intelligent fault judgment can be carried out, frequent error transformation between refrigerating and heating can be avoided, self-adaptive control can be realized, the working mode can be automatically switched, and the refrigeration operation of a machine unit under a low-temperature working condition can be met through sub-cooling degree control.